Lubricating oil additives



atent Patented Nov. 5, 1957 LUBRICATING OIL ADDITIV ES Robert H. Jones, Decatur, Ga., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Original application November 21, 1951, Serial No. 257,651, now Patent No. 2,765,277, dated October 2, 1956. Divided and this application October 28, 1955, Serial No. 543,597

6 Claims. (Cl. 260-132) This invention relates to mineral oil compositions and particularly to lubricants containing a detergent additive.

The present application is a division of Serial No. 257,651, filed November 21, 1951, and now issued as U. S. Patent 2,765,277.

Phospho-sulfurized hydrocarbons may be treated with guanidine or derivatives thereof to form lubricant additives that are stable under usual engine operating conditions and that have good detergent and anti-oxidant properties. Such additives are particularly desirable for use in certain engine lubricants because they contain no metal and thus do not form metallic deposits or ash on engine parts. However, it has been found that such additives are corrosive to certain metal parts, p articular ly to bronze, and in addition lubricants containing them tend to coke or otherwise decompose under extremely severe engine operation conditions. I

It has been found, in accordance with the present invention, that the properties of such materials may be improved by treating a guanidino derivative of a phosphosulfurized hydrocarbon with an oxide of lead. The resulting additive, although containing a metal constituent, is entirely satisfactory for use in many types of lubricants. The tendency of lubricants containing this additive to corrode bronze and other metal parts is relatively small. The detergency characteristics of the parent guanidino derivative are improved, and at the same time other desirable characteristics of the parent material are retained.

In accordance with the present invention, a guanidino derivative of a phospho-sulfurized hydrocarbon is treated with at least one oxide of lead, such as PbO, Pb304, PbzOa, and PbOz, although Pba04 is the preferred oxide, under conditions such that substantial amounts of lead are introduced into the additive. The reaction may be conducted in the presence of water or steam, but preferably it is carried out under substantially anhydrous conditions at temperatures in the range of about 250 F. to 500 F. or higher, the upper temperature being below that at which substantial decomposition of the material takes place. The amount of lead oxide employed in the treating step may vary over a rather wide range; generally sufiicient oxide is employed to form a reaction product having from about 1 to 25% or higher ash content, preferably about 5 to 20 weight percent ash. If complete neutralization of the guanidino compound is to be obtained, a considerable excess of the lead oxide will usually be required; The guanidino derivative may be reacted with other basic metallic compounds such as the oxides, sulfides, carbonates and hydroxides of antimony, copper, magnesium, and the like, but lead oxides are preferred.

It is preferred that the reaction mixture of lead oxide and guanidino derivative be blown with an inert gas such as nitrogen during the reaction step. Reaction time will vary considerably depending on the temperature of reaction, the amount and type of lead oxide used, and the limitations on quantity of ash which it is desired or is permissible to introduce into the additive. The resulting reaction product is preferably filtered through a diatomaetc.

ceous earth or other filtering means to remove insoluble containing materials.

The phospho-sulfurized hydrocarbon used in the present invention is one prepared by procedures well known to the art. Conveniently it is prepared by reaction of a hydrocarbon material with a sulfide of phosphorus such as P283, P285, P48 P487, and the like but preferably with phosphorus pentasulfide, P255. The phospho-sulfurization is generally carried out at a temperature of about 200 to about 600 F., and preferably from about 300 to about 550 F., using from about 1 to about 10, preferably about 2 to about 5,, molecular proportions of hydrocarbon to one molecular proportion of the sulfide of phosphorous. The reaction is preferably carried out in a nonoxidizing atmosphere, such as atmosphere of nitrogen. It is usually desirable to use an amount of phosphorus sulfide that will substantially completely react with the hydrocarbon such that further purification of the product is unnecessary. The reaction time is generally not critical, the time required being that necessary for substantial completion of the reaction, i. e., to cause substantially a maximum amount of the sulfide used to react under the temperature conditions employed. A reaction time from 2 to 10 hoursin the preferred temperature range of 300 to 550 F., is generally necessary. If desired, the reaction product may be further treated by blowing with steam, alcohol, ammonia, or the like at an elevated temperature in the range of about 200 to about 600 F. to improve the odor thereof.

A wide variety of hydrocarbon materials may be reacted with the phosphorus sulfide. Such reactive hydrocarbons include olefins, or olefin polymers, diolefins, acetylenes, aromatics, alkyl-aromatics, alicyclics, petroleum fractions, such as lubricating oil distillates, petrolatums, cracked cycle stocks, or condensation products of petroleum fractions, solvent extract of petroleum fractions, and the like. Particularly desirable, and preferred in the practice of the present invention, are petroleum lubricating oils such as cylinder oils and bright stock residuums. Non-asphaltic petroleum resins from crudeoil can also be used. Examples of monoolefins include isobutylene, decene, cerotene, olefinic extracts from gasoline, cracked waxes, etc. Monoolefin polymers having molecular weight ranges from about to 50,000 and obtained by the polymerization of low molecular weight olefins such as ethylene, isobutylene, and the like, are also suitable.

Aromatic hydrocarbons such as benzene, naphthalene, anthracene, xylenes, and others having alkyl substituents as Well as aliphatic hydrocarbons having aryl substituents may be employed. Condensation products of halogenated aliphatic hydrocarbons with an aromatic compound produced by condensation in the presence of a Friedel-Crafts type catalyst may be used, e. g. alkylated naphthalenes,

It is seen that a wide variety of hydrocarbon materials may be employed in preparing the phospho-sulfurized material. Preferred hydrocarbons are those having molecular weights above about 100.

The guanidino derivatives of the phospho-sulfurized hydrocarbon are prepared by known procedures. Preferably, they are made by neutralizing the titratable acidity of the phosphorus-sulfidehydrocarbon reaction product with a basic guanidino compound such as guanidine or derivative thereof. The free base guanidine audits derivatives may be used as well as basic acting salts of such bases, by which is meant salts of acids whose strength, measured on a pH scale, is less than the acidic phosphorus-sulfide-hydrocarbon product. Such basic acting salts include the carbonates of guanidine and its derivatives. The products may be formed by double decomposition of a salt of guanidine or guanidino derivative, such as guanidine hydrochloride or sulfate, with a metal salt of the phospho-sulfurized hydrocarbon reaction product. Although guanidine and its salts are preferred, substituted guanidine may be used.

Broadly, guanidine compounds used in the practice of the present invention may be defined by the formula:

in which R, R, and R" represent hydrogen or hydrocarbon groups containing 1 to 20 carbon atoms, e. g., straight chain alkyl groups, such as methyl, ethyl, propyl,

butyl, also higher straight and branched chain alkyl groups, such as octyl, isooctyl, Z-ethylhexyl, decyl, dodecyl, tetradecyl, cetyl and stearyl radicals. R, R and R" may also represent cycloalkyl, aralkyl, aryl or alkaryl groups, for example, methylcyclohexyl, phenylethyl, phenyl, cresyl, and tertiary-butylphenyl groups. It will be understood that R, R and R can be the same or different atoms or groups in the same molecule. However,

in the case of a substituted guanidine it is most preferable to employ symmetrically tri-substituted compounds, and

a-Methylguanidine a-Decylguanidine a,a-Diisoamylguanidinc a,a-Dicyclohexylguanidine a,a-Diphenylguanidine Triethylguanidine Tribenzylguanidine The substantially neutralized phospho-sulfurized hydrocarbon product is prepared by reaction with a basic guanidino compound of the above type preferably in a nonoxidizing atmosphere by contacting with the phospho-sulfurized material as such or dissolved in a suitable solvent such as naphtha at a temperature of about 100 to 400 F. It is generally desired to employ at least enough of the basic compound to neutralize the titratable. acidity of the phsopho-sulfurized-hydrocarbon product. In practice a somewhat greater amount of basic compound is generally used, since the basic compound may be reacted in proportions greater than that required for substantial neutralization of titratable acidity. When the basic compound is added in the form of a carbonate, the completion of the reaction is indicated by a cessation of carbon dioxide evolution. such as guanidine carbonate may be dissolved in water and then reacted with the phospho-sulfurized hydrocarbon.

- The guanidino derivative is then reacted with an oxide of lead or a mixture of oxides as heretofore stated. It

has been found surprisingly that the oxide of lead will not reactin any substantial proportions with the phosphosulfurized hydrocarbon per se, although the reaction between the lead oxide and the guanidino derivative proceeds smoothly.

The finished reaction product should be sufficiently soluble in the mineral oil base stock for use as an additive. The additive will preferably be added in proportions of about 0.01 to about 10.0 or 20.0 weight percent, based.

on the finished composition. Preferably about 0.1 to

6.0 weight percent will be used. It is convenient to prepare oil solutions in which the amount of additive in the,

Somewhat less preferable but still useful A water-soluble basic compoundcomposition ranges from about 20 to 50% by weight, and to transport and store the concentrate in such form. In preparing a lubricant for use in crank cases, the additive concentrate is merely blended with the base oil in the required amount. It will frequently be desirable to employ in the finished lubricant composition other types of additives that will improve certain characteristics. Such materials include pour depressors, sludge dispersers, antioxidants, viscosity index improvers, oiliness agents, and the like. The lubricating oil base stocks may be straight mineral lubricating oils or distillates derived from paraffinic, naphthenic, or mixed base crudes; the oils may be refined by procedures well known to the art. In many cases, the additives may be used in synthetic oils, such as the dibasic acid esters, glycol ethers, etc., and in mixtures of such synthetic oils with mineral oils. The oils may vary considerably in viscosity and other properties dc pending on the ultimate use, but usually the viscosity will range from about 40 to seconds Saybolt viscosity at 210 F. The oils may be used in lubricating automotive, airplane, and diesel engines. The additives may also find use in hydraulic fluids, cutting oils, turbine oils and the like where anti-oxidants are used. They may also be used in gear lubricants and greases for extreme pressure service.

' Below are given detailed descriptions of preparations of examples of lubricating oil additives described above as well as engine tests in which an oil containing the additives was used as a lubricant. It is to be understood that these examples are given as illustrations of the present invention and are not to be construed as ilimiting the scope thereof in any way.

Example 1 .Product A was prepared as follows: 665 gallons of phenol-extracted bright stock was charged to a reactor and heated to 250 F., nitrogen being blown through the oil and vigorous mechanical agitation being maintained during the entire heating period. 25 cc. of a silicone polymer was added to prevent foaming. 485 pounds of P285 were added over a 15 minute period and the entire mixture was heatedto 430 to 460 F. for about two hours, soaked at about 400 F. for three hours, and then filtered through Hi-flo, a commercial diatomaceous earth. 3,365 pounds of this product was charged to a reactor and heated to F., nitrogen blowing and mechanical agitation being maintained during the entire heating period. A solution of 387 pounds of guanidine carbonate in 752 pounds of water was prepared by heating the two components to to 200 F. This solution was then poured into the reactor and the temperature raised to 300 F. over a period of six hours and held at 310 to 330 F. for three hours additional. This product also was filtered through Hi-flo. The resulting guanidine salt of P255 treated bright stock contained no ash, substantially no sodium, and 3.23-3.87 weight percent nitrogen. It contained about 1.68 weight pcrcent of sulfur and 1.47 weight percent of phosphorus.

Example 2 Product B was prepared by treating 200 g. portion of the acidic P255 treated bright stock, prepared in accordance with the procedure described in Example I, but which had not been treated with guanidine carbonate, with 40 g. (20 weight percent) of PhD at 380 to 400 F., for three hours. The product was then filtered and was found to contain only 0.29 weight percent ash, showing that the lead oxide did not react to any substantial extent with the acidic phospho-sulfurized hydrocarbon.

Example 3 Product 0 was prepared by treatment of 200 g. of product A with 40 g. (20 weight percent) of PhD under the same conditions employed in the preparation of Product D was prepared by treatment of 200g. of product A with 20 g. (10 weigh percent) of sodium hydroxide dissolved in 30 cc. of water with heating for five hours at 250 to 350 F. The filtered product contained about 7.0 weight percent ash, 0.56 to 0.94 weight percent nitrogen and about 1.6 weight percent sodium.

Example Product E was prepared in the same way as product C except that 30 g. (15 weight precent) of Pb3O4 were used instead of PbO. The reactants were blown with nitrogen during the reaction period. The filtered product contained 15.4 weight percent ash and 0.97 weight percent nitrogen.

Example 6 Product F was prepared in the following manner: 3150 g. of P255 treated bright stock (prepared as described in connection with product A) were heated to 150-160 F., and treated with a solution of 170 g. of ammonium carbonate dissolved in 630 g. of water. The temperature was raised to 350 F. over a 4 hour period and maintained at this figure for one hour additional while being continuously stirred and blown with nitrogen. The product was filtered and 200 g. of the filtered material was heated to 150160 F. and treated with 50 g. of ammonium hydroxide. The product was again heated at 350 F., as described above, and finally filtered. The filtered product contained less than 0.01 weight percent ash.

Example 7 Product G was prepared by stirring 200 g. of product F with 20 g. weight percent) of Pb3O4 for 3 hours at 400410 F. with nitrogen blowing. The filtered product contained 7.5 Weight percent ash, and 0.07 weight percent nitrogen.

Example 8 The additives were subjected to a laboratory coking test carried out in the following manner: The test lubricant was placed in an aluminum measuring cup and stirred while heat was applied. The sidewalls were maintained at approximately 500 F. while the oil was heated from the bottom until it reached 550 F. The stirrer was then stopped for ten minutes followed by stirring for 10 minutes, and this procedure repeated until the end of the fourth non-stirring period. The oil was then discarded and the coke deposit weighed.

The additives Were also evaluated by a bronze corrosion test, in which each additive was dissolved in an aviation oil of 120 seconds Saybolt viscosity at 210 F. to form a solution containing 6% of the active ingredient. Each oil sample thus prepared was heated to 650 F. in the presence of a quarter-section of an aviation engine valve guide for a period of 17 hours. The loss in weight of the valve guide section was determined as milligrams weight loss per gram of metal.

The results of the above tests are shown in the following table:

The lead oxide-treated additives gave superior results in both resistanceto coking and anti-corrosion properties. Preparation of the product in an inert atmosphere improved the characteristics of the additive.

Example 9 Additives A and C were evaluated in a C. F. R. engine test, using as the base oil an aviation oil of seconds Saybolt viscosity at 210 F. The test samples of the oil blends contain 4% by Weight of the additive, and for comparison a sample of the unblended base oil was likewise tested. The test was conducted for a period of 50 hours, the C. F. R. engine being operated at 1800 R. P. M. and 4 brake horse-power. The oils were rated on a demerit system wherein a perfectly clean surface is given a rating of 0, while a rating of 10 is given to the worst condition which could be expected with that surface. The results obtained are shown in the following table:

Engine Demerits Wt. Percent Additive in Oil Overall Ring Varnish Ring Zone Sticking None -s 2. 5 5. 6 4. 0 2. 5 4% Product A 1.4 3. 2 2. 7 0. 0 4% Product G 1. 1 2. 6 1. 4 0.0

wherein R, R and R are selected from the group consisting of hydrogen and alkyl, cycloalkyl, aralkyl, aryl and alkaryl groups, said groups containing 1 to 20 carbon atoms; and (2) basic reacting salts of said guanidine compounds, the improvement of the coking and anticorrosion properties of said neutralized phospho-sulr'urized hydrocarbon which comprises further reacting said neutralized phospho-sulfurized hydrocarbon with an oxide of lead at temperatures above 250 F. and below the decomposition temperature of said neutralized phospho-sulfurized hydrocarbon to form a lead-containing product which yields an ash content of about 1 to 25 weight percent.

2. An additive according to claim 1 in which said reaction with lead oxide is carried out at a temperature in the range of about 250 to about 500 F.

3. In a process which comprises neutralizing a phospho-sulfurized hydrocarbon with a guanidino compound selected from the group consisting of (1) guanidine compounds having the formula:

wherein R, R, and R" are selected from a group consisting of hydrogen and alkyl, cycloalkyl, aralkyl, aryl and alkaryl groups, said groups containing 1 to 20 carbon atoms; and (2) basic reacting salts of said guanidine compounds, the improvement which comprises further reacting said neutralized phospho-sulfurized hydrocarbon with an oxide of lead at temperatures of about 250 to 500 F. to form a lead-containing product having an ash content of about 1 to 25 weight percent.

I s .4. A process according to claim 3 wherein said oxide pentasulfide with about 1 to 10 molar proportions'of a of lead is PbO. lubricating oil bright stock reacted at 'a temperature of 5. A process according to claim 3 in which said oxide about 200 to 600 F. for about 2 to '10 hours. of lead 18 I References Cited in the file of this patent 6. A composition of matter according to claim 1 5 wherein said phospho-sulfurized hydrocarbon is the re- UNITED STATES PATENTS action product of one molar proportion of phosphorus 2,613,205 Hill Oct. 7, 1952 

1. IN A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A PHOSPHO-SULFURIZED HYDROCARBON NEUTRALIZED WITH A BASIC REACTING GUANIDINO-TYPE COMPOUND SELECTED FROM THE GROUP CONSISTING OF (1) GUANIDINE COMPOUNDS HAVING THE FORMULA: 